/Engine/Plugins/Online/OnlineFramework/Source/Rejoin/Public/RejoinCheck.h
Check the backend for the existence of game session that the local player is registered with It will continue to return a valid value until that session is complete
virtual void CheckRejoinStatus ( const [FOnRejoinCheckComplete](API\Plugins\Rejoin\FOnRejoinCheckComplete) & CompletionDelegate )